A. Field of the Invention
This invention relates to biological reaction systems, and more particularly relates to an improved dispenser for use in conjunction with an automated biological reaction system.
B. Description of Related Art
Immunostaining and in situ DNA analysis are useful tools in histological diagnosis and the study of tissue morphology. Immunostaining relies on the specific binding affinity of antibodies with epitopes in tissue samples, and the increasing availability of antibodies which bind specifically with unique epitopes present only in certain types of diseased cellular tissue. Immunostaining requires a series of treatment steps conducted on a tissue section mounted on a glass slide to highlight by selective staining certain morphological indicators of disease states. Typical steps include pretreatment of the tissue section to reduce non-specific binding, antibody treatment and incubation, enzyme labeled secondary antibody treatment and incubation, substrate reaction with the enzyme to produce a fluorophore or chromophore highlighting areas of the tissue section having epitopes binding with the antibody, counterstaining, and the like. Each of these steps is separated by multiple rinse steps to remove unreacted residual reagent from the prior step. Incubations are conducted at elevated temperatures, usually around 40° C., and the tissue must be continuously protected from dehydration. In situ DNA analysis relies upon the specific binding affinity of probes with unique nucleotide sequences in cell or tissue samples and similarly involves a series of process steps, with a variety of reagents and process temperature requirements.
Automated biological reaction systems include the biological reaction apparatus and the dispensers for the reagents and other fluids used in the biological reaction apparatus. As disclosed in U.S. Pat. No. 5,595,707, inventors Copeland et al., entitled Automated Biological Reaction Apparatus, assigned to Ventana Medical Systems, Inc. which is incorporated herein by reference, the biological reaction apparatus may be computer controlled. However, the computer control is limited in that it is dedicated to and resident on the biological reaction apparatus. Moreover, the memory, which is used in conjunction with the computer control, contains data relating to the reagents including serial number, product code (reagent type), package size (250 test), and the like.
One of the requirements in a biological reaction system is consistency in testing. In particular, the biological reaction system should apply a predetermined amount of fluid upon the slide in order to consistently test each slide in the automated biological reaction apparatus. Therefore, an important focus of a biological reaction system is to consistently and efficiently apply a predetermined amount of fluid on the slide.
Further, as disclosed in U.S. Pat. No. 5,232,664 entitled Liquid Dispenser by inventors Krawzak et al. and assigned to Ventana Medical Systems, Inc., which is incorporated herein by reference, reagents must be dispensed on the slide in precise amounts using a fluid dispenser. The fluid dispenser, which is used in conjunction with the biological reaction apparatus, should be easy to manufacture, reliable and compact in size.